Organic routes for the preparation of aminonitriles are known and one class of reactions involves the formation of the .alpha.-trimethylsilyloxy nitrile by the addition of trimethylsilyl cyanide (TMSCN) to an aldehyde in the presence of a Lewis acid, such as zinc iodide. (See, for example, Y. Safran et al., Russ. Chem. Rev., 58:148 (1989); P. G. Gassman et al., Tetrahedron Letters (1978) No. 40, pp. 3773-3776; K. Mai et al., Tetrahedron Letters (1984) 25, No. 41, pp. 4583-4586; and U.S. Pat. No. 4,551,526).
A non-catalytic method for making .alpha.-aminonitriles is described by K. Mai et al. in Synthetic Communications, 15(2) 157-163 (1985). This method involves a double stoichiometry of aldehyde or ketone and TMSCN and requires thermal energy. The process entails the heating of two moles of aldehyde or ketone with one mole of amine at 100.degree. C., followed by cooling to room temperature, the addition of two equivalents of TMSCN, and the heating of the resulting reaction mixture to 100.degree. C. again.
In Organic Preparations and Procedures Int., 17, 183-186 (1985) K. Mai et al. proposed use of a somewhat milder reaction that still necessitated the use of thermal energy, i.e., the condensation of the aldehyde and amine in refluxing methanol. This procedure also involved the use of an excess of the aldehyde (33%) and of the TMSCN (100%).